Referring to FIG. 1, a perspective view of a prior art bulb 1 is illustrated. The prior art bulb is formed by a seat 11, a bulb base 12, a light emitting diode 14, and a lampshade 13. The seat 11 is installed with a circuit board therein. When the circuit board is conducive, heat will generate so as to have a high temperature. However high temperature will induce errors in operation. The bulb base 12 is a sealing body. A backside of the bulb base has a via hole 15. The via hole 15 is used for dissipating heat. In the prior art, the size of the via hole 15 is very small. Furthermore, in the prior art, bulb is made of plastics which is not a preferred heat dissipation object so that heat in the bulb can not be dissipated fully. Thereby there are too many light emitting diodes 14 are installed so that generated heat can not be completely dissipated. As a result, heat will affect the light emission so that the illumination is low.
Thus, in the prior art light emitting diode has a small volume, short light time and low power so that it is used as indicators, or displays, or auxiliary brake lights or traffic signals or traffic lights. In general, the prior art LEDs are bad in heat dissipation so that only a small power is generated. If it is desired to enlarge the size of the LEDs, the cost will increase. Moreover, LED lights use metal as support and for dissipating heat, but it is not sufficient. As a result, heat accumulated will burn the chips of the bulb and package of the bulb so as to reduce the illumination of the bulb to reduce the lifetime of the bulb.